The overall objective of this project is to develop a good inhibitor of angiotensin-converting enzyme that would be resistant to decomposition if administered orally in man. Because such a compound would be expected to have antihypertensive properties, it might ultimately be used to treat people with chronic high blood pressure. Proposed is the synthesis of nonpeptide analogs of known peptide inhibitors of angiotensin-converting enzymes. As nonpeptides, these compounds would be expected to withstand the degradative enzymes in the gastrointestinal tract of man. These compounds will be tested for their ability to inhibit angiotensin-coverting enzyme in an in vitro test system. Those compounds that show good inhibitory activity will be tested further for their ability to lower blood pressure in renal hypertensive rats.